New here, and I'm having a bit of an issue. I have a Mazda 3 2.0i w/ 85,000 miles.

Last Saturday, the car wouldn't turnover (partially due to the cold, partially due to it having a 5 year old battery). After a jump, I headed to Autozone, and put in their 'gold' level battery, and it starts like a charm. The bad news, it now stalls out when approaching stops. When my foot is not on the throttle, the RPM's go down to around 400-600 and bounce around when I driving under 30 mph or so. Sometimes they go up to 1,000 - 1,200, and sometimes it stalls out. I have no CEL (aside from when it stalls, when a whole bunch of lights pop up) and I was told by my local auto zone that they can't read what's going on if the CEL isn't on at the moment.

I brought it to my local dealership, got the 60,000 mile service and replaced a cracked motor mount. I told them about the issue, but they were unable to recreate it. I pointed them to the two TSB's (found through this site!) that greatly detail exactly how common this issue is and how to fix (PCM flash, which I was told was done with the 60k service and cleaning of the throttle body, which they said they checked). They also told me that after I unplugged the battery, I reset the cars computer, and it might take some time to relearn how the car has aged.

After two more days of continued stalling when slowing down, I brought it back to the dealership, and they recommended I get a fuel service where they clean the injectors. They AGAIN couldn't recreate the problem. I find this almost impossible to believe as I can't drive my car around the block with out noticing at least some odd RPM fluctuations.

So my questions are, how common is the problem of the fluctuating RPM's after changing a battery. Is this something that affects all cars? I can't imagine (for the life of me) someone at Mazda thinking it's a good idea to have a car act they way mine is acting after unhooking the battery. I'd think when weighing the pro's and con's with how our cars are built, the question &quot;Does it have issues after unhooking the battery that might cause an accident&quot; would be pretty high on the con list.

Also, what's my best bet? Take it to another dealership: I'm not going back to the last one if they can't even recreate the problem, and I'm not 100% confident in their work. This is kind of funny because I was impressed that they found a cracked motor mount in my car. It led me to believe that they must have really looked over every aspect of my engine... until i logged onto this sight and saw that everyone and their mother seems to have problems with the motor mounts. Now I think they were scummy for charging me for replacing it and not applying my warranty (I have full coverage warranty up to 100k/2012 which I didn't know about until after).A private mechanic: My concern here is they might not be familiar with the one-offs that affect only this model carBe more patient: it's been a week since I changed the battery, started it up and drove 15-20 times, with multiple stalls both timesBite the bullet and get the fuel injectors cleaned: this was the recomendation of the dealership, but from searching through this forum, I haven't seen a stalling issue fixed by this. I wouldn't be doing this myself as I'm not mechanically inclined, and it's going to be frigid the next few days.

I've searched around and read other people's stories. Most ended with people either cleaning the throttle body (which my dealership said was fine) or having the dealership flash the car's computer. While it's nice to see other people also have my problem, I haven't seen anyone recomend cleaning the fuel injectors. Could this be the issue? And if they need cleaning would a CEL be there?

I've had this happen a few times when I've either pulled the battery or just disconnected for some electrical work. After about two days (two-three drive cycles) mine stops stalling and operates as normal. It's just the computer relearning the car. Your fuel injectors are fine, if there was a problem with you'd also notice it while driving and not just at idle.

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[quote author=dugger_8 link=topic=185249.msg3914080#msg3914080 date=1295810266]
I've had this happen a few times when I've either pulled the battery or just disconnected for some electrical work. After about two days (two-three drive cycles) mine stops stalling and operates as normal. It's just the computer relearning the car. Your fuel injectors are fine, if there was a problem with you'd also notice it while driving and not just at idle.
[/quote]

Good call on the fuel injectors. Didn't think of that.

Two other questions for everyone out there.

Would disconnecting the negative terminal of the battery for 5 minutes or so, to reset the cars computer be useful? Wouldn't hurt right?

Also, if not ECU related, would it likely be related to the air flow going into the engine? Part of me wants to take it to another dealership/mechanic and have them look at the throttle body TSB, as the people who 'checked' it don't inspire confidence in me. Is it possible a car in the northeast wouldn't have a dirty throttle body after 80k miles?

I also have a 2.0L but mine has 82,000 miles. I recently changed my battery, and right after my car stalled out several times. After a few trips it got tolerable, but was always hunting for a decent idle. Things then got worse, as when I would be approaching a stop my rpm's would go up and down, like someone was pressing and letting off the gas. Essentially the ideal was just fubar.

I disconnected the battery and started fresh again, and a day later most of the problems were back. I honestly felt the battery was fine, but the car was not re-learning the idle properly. I looked into the throttle body.

I will warn you, when you (or a mechanic) pull your air hose to expose the right side of the throttle body, it will be clean. This side is not the issue, as it's dealing with the air going through the filter. Some on here have checked the throttle body and scratch their head because it appears to be clean.

Well, actually take the throttle body off. The left side of the TB will be soaked, and I mean soaked with carbon build-up. This is the side you can't see until you take it off. I had such bad buildup that my car could not get a decent idle. So I cleaned out the entire TB with a Mazda cleaner (it's mentioned in the TSB). 100% clean, and bolted it back up, and reconnected the battery.

Results? Flawless idle. My car had a ok idle until 82k, had one or two hiccups but never a stall. When I replaced the battery that went fine, but the car at that point could not relearn the idle with such a messed up throttle body. Now that my throttle body is clean, the car runs like new.

So bottom line don't get that fuel injector service, it will do nothing (go buy some Redline Si-1, it'll do more than whatever they do). Clean that throttle body, and I mean take it off and clean it good. Ideally do it yourself, but if not take it to a trusted mechanic and have them actually take it off. I can't promise you that will fix it, but your car and situation is so similar to mine, it's by far the best option before anything else.

i took TB off yesterday and it was charcoal-black on the inner side ;-(
did not expect that on a 4-year old car with 33K miles
cleaned it with a rug soaked in 100% ethanol, took about 25 min to remove all carbon deposit.
the difference - like night and day :-)

[quote author=Dimon aggie link=topic=185249.msg3920582#msg3920582 date=1296503425]
i took TB off yesterday and it was charcoal-black on the inner side ;-(
did not expect that on a 4-year old car with 33K miles
cleaned it with a rug soaked in 100% ethanol, took about 25 min to remove all carbon deposit.
the difference - like night and day :-)
[/quote]

Is it hard getting to the TB ?
I'm afraid mine might be like yours. ._.

I replaced my battery last winter and the engine idled roughly for 2 to 3 days. The guy at Autozone warned me about the rough idle so I was looking for it. Everything was back to normal after several starts and stops. I have not experienced the same thing with other cars. Interesting note about the throttle body. I will keep an eye out in case my idle starts acting strange again.

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